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14
Nutrition and
Physical Activity:
Keys to Good
Health
© 2011 Pearson Education, Inc.
Physical Activity vs. Fitness
• Physical activity: any movement produced by
muscles that increases energy expenditure
• Leisure-time physical activity: any activity
unrelated to a person’s occupation
• Competitive sports
• Recreational: hiking, walking, biking
• Exercise: purposeful, planned, and structured
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Physical Activity vs. Fitness
• Physical fitness: state of being from
interaction between nutrition and physical
activity
• Physical fitness includes cardiorespiratory
fitness, musculoskeletal fitness, flexibility
• Body composition is the amount of bone,
muscle, and fat tissue in the body
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
Benefits of Physical Activity
• Reduces the risk of heart disease, stroke,
high blood pressure
• Reduces the risk for obesity and type 2
diabetes
• Reduces the risk for osteoporosis
• May reduce the risk of colon cancer
• Improves sleep patterns, immune function
• Reduces anxiety and mental stress
© 2011 Pearson Education, Inc.
Benefits of Physical Activity
• Despite the clear benefits of regular physical
activity:
• Most Americans are physically inactive
• 16% of U.S. adults experience no leisure-time
physical activity
• Less than 30% of high school students participate
in daily physical education
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
Sound Fitness Program
• Meets personal goals
• Is varied, consistent, and fun
• Physical Activity Pyramid recommends the
type and amount of activity
• Includes aerobic-type activities and resistance
training
• Appropriately overloads the body
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
The FIT Principle
• Frequency—number of activity sessions per
week
• Intensity—amount of effort expended or how
difficult the activity is to perform
• Estimating maximal heart rate
• Borg Scale of Perceived Exertion: rating of
perceived exertion (or RPE)
• Time of activity—how long session lasts
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
Warm-up and Cool-down Period
• To properly prepare for and recover from an
exercise session
• Warm-up increases blood flow and
temperature, and prepares a person for the
activity (5 to 10 minutes)
• Cool-down helps to prevent injuries and may
reduce muscle soreness
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Fuel for Physical Activity
• Adenosine triphosphate (ATP): the energycarrying molecule in the body
• ATP must be generated continuously since
muscles store only enough ATP for 1–3
seconds of activity
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
Fuel for Physical Activity
• After depleting ATP stores, muscles turn to
other sources:
• Creatine phosphate (CP) stores some energy
that can be used to make ATP
• CP stores enough energy for 3−15 seconds of
maximal physical effort
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
Fuel for Physical Activity
• After creatine phosphate, glucose is the next
source of energy for ATP production
• Glucose provides ATP through glycolysis
• Glucose source during exercise: muscle
glycogen and blood glucose
• Glycogen stores are limited
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Fuel for Physical Activity
• Primary glycolysis end product: pyruvate
• With limited oxygen, pyruvate is converted to
lactic acid, a by-product of intense activity
• Excess lactic acid goes back to the liver to be
converted back into glucose
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
Fuel for Physical Activity
• Glucose metabolism
• Anaerobic breakdown of glucose yields 2 ATP
molecules
• Aerobic breakdown of glucose yields 36–38
molecules of ATP
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Fuel for Physical Activity
• Triglycerides (fats) can be metabolized to
generate ATP
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For low-intensity exercise
For exercise of long duration (marathons)
Abundant energy source, even in lean people
2x more energy per gram as carbohydrates
Slow in breaking down
Primary energy source during rest, sitting, and
standing in place; also endurance events
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Fuel for Physical Activity
• Carbohydrates and fats can both be used as
energy sources for ATP production
• Carbohydrates are mostly used for high-intensity
activity
• Fats are used for low-intensity exercise
• Proteins (amino acids) are not used as a fuel
source for exercise
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
Energy Needs
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Vigorous exercise increases energy needs
Higher for athletes
Different energy needs for males, females
Needs depend on body size
Needs depend on the type of physical activity
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
Carbohydrate Needs
• Athletes should consume carbohydrate
intakes: 45−65% of total energy
• Following exercise: consuming carbs with
protein enhances muscle protein synthesis
• Optimize glycogen storage: first 4−6 hours of
recovery
• Complex, less-processed carbohydrates:
whole grains, fruits, and vegetables supply
fiber, vitamins, and minerals
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
Carbohydrate (Glycogen) Loading
• Alter exercise duration and carbohydrate
intake to maximize muscle glycogen
• Does not always improve performance
• Side effects: gastrointestinal distress; feeling
heavy, bloated, and sluggish
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
Training Effects on Fat Metabolism
• Increased number and activity of enzymes
involved in fat metabolism
• Improved ability of muscles to store fat
• Improved ability to extract fat from the blood
for use during exercise
• Spares carbohydrate for prolonged, intense
training or competition
© 2011 Pearson Education, Inc.
Protein Needs
• Increased protein needs for competitive,
endurance, and resistance athletes
• Individuals who are already trained need less
protein than those who are initiating training
• Recreational endurance athletes’ protein need
is equal to or slightly higher than the RDA
• Individuals with very low energy intakes
• Vegetarians consuming low-protein foods
• Young athletes who are growing
© 2011 Pearson Education, Inc.
Protein Needs
• High-protein, low-carbohydrate diet marketed
for athletes: NOT recommended
• Too low in energy and carbohydrates to support
training and performance
• People of all fitness levels can consume
enough protein foods without using
supplements or specially formulated foods
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
Fluid Needs
• Functions of water
• Lubricant that bathes tissues and cells
• Transportation of nutrients, hormones, waste
products
• Component of chemical reactions
• Part of body tissues (proteins and glycogen)
• Temperature regulation: evaporative cooling
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Water Balance
• Heat syncope: dizziness
• Heat cramps: muscle spasms
• Heat exhaustion and heatstroke occur on a
continuum; symptoms include:
• Excessive sweating, weakness, nausea,
dizziness, headache, difficulty concentrating
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
Proper Fluid Replacement
• Drink fluids before, during, and after exercise
• Thirst mechanism not reliable
• Drink enough to maintain body weight
© 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
Vitamins and Minerals
• Requirements for some vitamins and minerals
may be altered in athletes
• B-vitamins
• Calcium and the female athlete triad
• Iron
• Iron supplementation may be required under
proper medical supervision
• Most nutrient needs can be met with a healthy
diet
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Ergonomic Aids
• Substances used to improve exercise and
athletic performance
• Many are not effective
• Some have harmful side effects
• Most are very expensive
• Many have not been adequately studied
© 2011 Pearson Education, Inc.
Ergonomic Aids
• Anabolic products promoted as muscle and
strength enhancers
• Anabolic steroids
• Androstenedione (“andro”) and
Dehydroepiandrosterone (DHEA)
• Gamma-hydroxybutyric acid (GHB)
• Creatine
© 2011 Pearson Education, Inc.
Ergonomic Aids
• Ergonomic aids used to increase energy
levels and optimize fuel use include:
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Caffeine
Ephedrine
Carnitine
Chromium
Ribose
© 2011 Pearson Education, Inc.